KR101214422B1 - Oxide sintered compact for producing transparent conductive film - Google Patents

Abstract

As an ITO-based amorphous transparent conductive film used for display electrodes for flat panel displays, etc., it can be manufactured without substrate heating without hydrogenation in sputtering, thereby providing a transparent conductive film that satisfies both high etching resistance and low resistivity in a high dimension. do. It contains indium oxide as a main component and contains 1 or more types chosen from nickel, manganese, aluminum, and germanium as a 1st addition element, and the sum total of content of a 1st addition element is 2-with respect to the total amount of indium and a 1st addition element. It is 12 atomic%, The oxide sintered compact.

Description

Oxide sintered compact for transparent conductive film production {OXIDE SINTERED COMPACT FOR PRODUCING TRANSPARENT CONDUCTIVE FILM}

The present invention relates to an oxide sinter for producing a transparent conductive film, which is formed as an electrode in a flat panel display or the like. Moreover, this invention relates to the transparent conductive film obtained using this oxide sintered compact as a sputtering target, and its manufacturing method.

Indium Tin Oxide (ITO) films are used in a wide range of fields, including display electrodes for flat panel displays, because they have superior characteristics such as low resistivity, high transmittance, and easy micromachining. At present, most of the ITO film-forming methods in industrial production processes are so-called sputter film-forming methods in which the ITO sintered body is sputtered as a target because uniformity and productivity can be produced well in a large area.

In a flat panel display manufacturing process using an ITO transparent conductive film, the ITO film crystallinity immediately after sputtering is amorphous, and microprocessing such as etching is often performed in an amorphous state, and the ITO film is often crystallized by subsequent open annealing treatment. . This is because the ITO amorphous film is advantageous in production because the etching rate is significantly larger than the crystal chamber film, and the ITO crystal film can enjoy both advantages of low resistivity.

Almost all of the films obtained by sputtering an ITO target are amorphous, but some of them are crystallized in many cases. The reason is that the crystallization temperature of the ITO film is about 150 ° C., and since most of the film is amorphous because it is only a temperature below this, some of the particles flying from the sputter to the substrate have a considerably high energy. It is because the temperature of a film | membrane becomes high temperature more than a crystallization temperature by the transfer of energy, and the part which a film crystallizes occurs. In this way, when a portion crystallized in a part of the ITO film occurs, the portion has an etching rate of about two orders of magnitude smaller than that of the amorphous portion, so that during subsequent etching, it remains as a so-called etching residue and causes problems such as wiring short.

Therefore, it is known that it is effective to add water (H ₂ O) in addition to a sputter gas such as argon in the chamber during sputtering as a method of preventing crystallization of the sputter film and making all of the sputter films amorphous (for example, For example, see Nonpatent Literature 1).

However, there are a number of problems with the method of obtaining an amorphous film by sputtering in adding water. First, particles are often generated in the sputter film. Particles adversely affect the flatness and crystallinity of the sputter film. Since no particles are generated unless water is added, the problem of particle generation is caused by the addition of water.

In addition, since the water concentration in the sputter chamber gradually decreases with the passage of the sputtering time, even if the water concentration is initially appropriate, the water concentration gradually falls short of the proper concentration, and a part of the sputter film crystallizes.

On the other hand, on the other hand, in order to reliably obtain an amorphous sputtered film, when the water concentration to be added is made high, the crystallization temperature at the time of the film crystallization in subsequent annealing becomes very high, and the problem that the resistivity of the film obtained becomes very high arises.

In short, in order to make all the sputter films amorphous, according to the sputter by adding water, it is always necessary to grasp and control the water concentration in a chamber, but it is very difficult and requires great effort and effort. It is.

As an attempt to solve such a problem, an amorphous stable transparent conductive material is used in some, not an ITO film in which a crystalline film is easily produced. For example, it is known that an amorphous film is obtained by sputtering the target with a sintered compact having a composition in which zinc is added to indium oxide, but the resistivity of the film is higher than that of the ITO film crystallized at about 0.5 m? Cm. In addition, the film has an average visible light transmittance of about 85% and is separated from the ITO film. In addition, there is a disadvantage that the moisture resistance of the membrane is bad.

As a prior art which started obtaining an amorphous film without adding water or zinc, the following is mentioned.

PTL 1 describes a transparent conductive film comprising indium oxide and tin oxide as main components and containing at least one metal oxide selected from the group consisting of magnesium and nickel. As a result, the film becomes dense, and the electron mobility becomes large about 1.5 × 10 cm 2 s ⁻¹ −V ⁻¹ . Moreover, it is also described that moisture resistance and ultraviolet resistance can be improved by adjusting the addition ratio of magnesium or nickel suitably. It is described that it is preferable that the compounding ratio of the magnesium compound or the nickel compound to the indium compound is 0.05 or less when converted to indium, magnesium or nickel M and represented by the formula M / (M + In).

Patent Document 2 discloses that the resistivity of a transparent conductive film is lowered by adding nickel oxide to indium oxide. By setting the addition amount of nickel oxide to 2 to 25 mol%, the specific resistance becomes 2 x 10 < ^-4 >

PTL ³ provides a target for providing an indium oxide-based sputtering target for a high resistance transparent conductive film having a resistivity of about 0.8 to 10 × 10 ^-3 Ωcm, and a target containing an insulating oxide in indium oxide or tin-doped indium oxide. This is described and manganese oxide is mentioned as an example of an insulating oxide. However, Patent Document 3 does not describe a sputtering target for obtaining a low resistance conductive film.

Patent Document 4 discloses a target in which manganese is added to indium oxide or tin-doped indium oxide because the sintered compact including manganese can achieve a very high sintered density in a sintered compact made of indium oxide and tin oxide. . It is described that manganese is adjusted so that content in the finally obtained ITO sintered compact may be 5-5000 ppm. The content of manganese is preferably 10 to 500 ppm, and only a maximum of 500 ppm is added even in the specific examples.

Patent Document 5 discloses that the resistivity of a transparent conductive film is decreased by adding manganese oxide to indium oxide. By setting the addition amount of manganese oxide to 2 to 15 mol%, the specific resistance becomes 2 x 10 ^-4 Ωcm or less, which is considered to be preferable.

In patent document 6, the film | membrane which contains a trivalent cation in indium oxide is shown, and aluminum is mentioned as an example. By doing so, it is described that a transparent conductive film having improved etching characteristics can be obtained at a lower resistance. However, the purpose of patent document 6 is to prevent the fall of mobility by ionization impurity scattering, and to obtain low resistivity and workability. Moreover, in the Example, there is only an example of yttrium. Thus, it is completely unclear whether aluminum has the effect as claimed in this patent application.

Patent Document 7 describes, "As a transparent conductive film containing an oxide of In as a main component, one containing Ge, or one containing Ge and Sn, becomes an amorphous film, which is easy to etch and excellent in workability. 0015). This is because "under certain constant film formation conditions, the addition of Ge is In ₂ O ₃ It is effective for the amorphousization of the film and does not impair the electrical resistivity and the transmittance of the film ”(paragraph 0021). Such film formation conditions are“ the film formation temperature is 100 to 300 ° C., and the amount of Ge is added to the amount of Ge and In. It is set to 2 to 12 atomic% with respect to the sum of the amounts, and the film is formed with an oxygen partial pressure of 0.02 mTorr or more '' (paragraph 0029). "At this time, when film-forming temperature is less than 100 degreeC and Ge addition amount is less than 2 atomic%, the fall of the electrical resistivity by carrier electron emission by Ge will not be enough, and an electrical resistivity will exceed 0.01 ohm-cm." Paragraph 0030 is also described.

Japanese Patent Application Laid-Open No. 07-161235 Japanese Patent Application Laid-Open No. 03-71510 Japanese Laid-Open Patent Publication 2003-105532 Patent number 3496239 Japanese Patent Application Laid-Open No. 03-78907 Japanese Patent Application Laid-Open No. 08-199343 Patent No. 3780100

 Thin Solid Films 445 (2003) p 235 ～ 240

As described above, as a prior art, using a sintered compact having a composition in which zinc is added to indium oxide as a target has a drawback that the film resistivity is high, and therefore, the solution is not sufficient.

Moreover, in any of patent documents 1-7, the transparent conductive film which fully satisfies both high etching property and low resistivity is not obtained, and there exists still room for improvement.

Then, the subject of this invention is an ITO-type amorphous transparent conductive film used for the display electrode for flat panel displays, etc., and can manufacture it, without the addition of a hydrogenation at the time of sputter | spatter by heating a board | substrate, and both high etching property and low resistivity improvement are attained. It is to provide a transparent conductive film which satisfies in a high dimension. Moreover, another subject of this invention is providing the sputtering target which can manufacture such a transparent conductive film.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining about the oxide target which added various elements to indium oxide or indium dope indium oxide, the present inventors found that the technical idea of the increase of the etching rate of a film by the addition of appropriate concentration of an appropriate dopant, and the low resistivity of a film is made. As a result, by sputtering a sintered body in which nickel or the like is appropriately added to indium oxide or tin-doped indium oxide under predetermined conditions, it was found that a transparent conductive film capable of solving the above problems was obtained, and completed the present invention.

The present invention completed on the basis of such knowledge can be specified as follows.

1) It contains indium oxide as a main component and contains 1 or more types chosen from nickel, manganese, aluminum, and germanium as a 1st addition element, and the sum total of content of a 1st addition element is with respect to the total amount of indium and a 1st addition element. It is 2 to 12 atomic%, The oxide sintered compact characterized by the above-mentioned.

2) It contains indium oxide as a main component, contains at least one selected from nickel, manganese, aluminum and germanium as the first additional element, contains tin as the second additional element, and the sum of the contents of the first additional element It is 2-12 atomic% with respect to the total amount of indium, a 1st addition element, and tin, and content of tin is 2-15 atomic% with respect to the total amount of indium and tin.

3) A method for producing an amorphous film, wherein the oxide sintered body according to 1) or 2) is used as a sputtering target.

4) An amorphous film having the same composition as the oxide sintered body according to 1) or 2) above.

The 1st characteristic of this invention is the surface which prevents crystallization by the effect that the added nickel etc. cut | disconnect network structure bonds, such as indium oxide. Moreover, the 2nd characteristic of this invention is the aspect which improves the etching characteristic while contributing to the low resistivity of a film | membrane simultaneously when such a dopant which promotes such amorphousization is carried out. Moreover, the 3rd characteristic of this invention is the aspect which can further promote the low resistivity of a film | membrane by adding tin further.

According to the present invention, a sputtering target in which nickel or the like is added at an appropriate concentration, such as indium oxide, is used to sputter film formation under predetermined conditions in a substrate-free state without adding water at the time of film formation. You can get a film. Moreover, since the obtained film | membrane is amorphous all and has a fast etching rate, since it is excellent in productivity and low resistivity of a film, it is suitable as a transparent conductive film.

Oxide sintered and transparent Of the conductive film  Furtherance

Nickel, manganese, aluminum, and germanium as the first addition elements, when added to indium oxide or indium-doped indium oxide, have the effect of preventing the film from crystallization and making the film amorphous. These may be added independently and may add 2 or more types. However, if the sum total of content of a 1st addition element is too small with respect to the total amount of indium and a 1st addition element (total amount of indium, a 1st addition element, and tin, when doping tin), the effect which will amorphousize a film | membrane Almost no, the sputtered film partially crystallizes. Therefore, the etching rate becomes small and etching residues generate. On the contrary, if the sum total of content of a 1st addition element is too large with respect to the total amount of indium, a 1st addition element, and (tin), the resistivity of an amorphous film will become high.

Therefore, the sum total of content of a 1st addition element shall be 2-12 atomic% with respect to the total amount of indium, a 1st addition element, and (tin), and it is preferable to set it as 4-8 atomic% from a viewpoint of obtaining a low film resistivity. It is more preferable to set it as 5 to 7 atomic%.

Nickel is preferable among the first addition elements. This is because nickel has a higher effect of lowering the resistivity of the amorphous film compared with other first additive elements, and also has a large function of increasing the etching rate.

When tin is added to indium oxide, it acts as an n-type donor and has an effect of lowering the resistivity. Commercially available ITO targets and the like usually have tin concentration Sn of about 10 atomic% with respect to the total amount of indium and tin. If the tin concentration is too low, the electron supply amount is small. On the contrary, if the tin concentration is too high, electron scattering impurities are caused, and in any case, the resistivity of the film obtained by the sputtering is increased. Therefore, tin concentration Sn suitable as ITO is 2-15 atomic% with respect to the total amount of tin indium and tin, Preferably it is 8-12 atomic%.

Manufacturing Method of Oxide Sintered Body

The manufacturing method of an oxide sintered compact is demonstrated below.

In order to manufacture the oxide sintered compact of this invention, the indium oxide powder which is a raw material, the oxide powder of a 1st addition element, and a tin oxide powder are weighed and mixed as needed at a predetermined ratio as needed. If the mixing is insufficient, high-resistance regions and low-resistance regions exist due to segregation of the first additive element in the produced target, and abnormal discharge such as arcing due to charging in the high resistivity region is likely to occur during sputter film formation. Although a thing other than the form of an oxide may be used as a raw material, An oxide is preferable from a viewpoint of handling.

Therefore, it is preferable to perform a sufficient mixing of about 2 to 5 minutes at a high speed rotation of about 2000 to 4000 rotations every minute using a super mixer for mixing. In addition, since the raw material powder is an oxide, the atmospheric gas may be in the air since the consideration of preventing oxidation of the raw material is not particularly necessary.

Moreover, it is also effective to put in 1250-1350 degreeC the calcination process of 4-6 hours hold | maintain in this atmosphere, and to promote the solid solution between raw materials at this stage. Moreover, you may calcinate indium oxide and the oxide of a 1st addition element as a mixed powder.

Next, the finely divided powder is mixed. This is for uniform dispersion in the target of the raw material powder, and the presence of the raw material powder having a large particle diameter causes composition unevenness depending on the place.

Therefore, it is preferable to perform grinding | pulverization until the particle size of a raw material powder becomes an average particle diameter (D50) 1 micrometer or less, Preferably it is 0.6 micrometer or less. In reality, water is added to the mixed powder to form a slurry having a solid content of 40 to 60% by weight, and fine grinding is performed for about 1.5 to 3.0 hours with zirconia beads having a diameter of 1 mm.

Next, the mixed powder is granulated. This is for making the fluidity | liquidity of a raw material powder good, and making the filling situation at the time of press molding good enough. PVA (polyvinyl alcohol), which acts as a binder, was mixed at a ratio of 100 to 200 cc per kg of slurry, and the inlet temperature of the granulator was 200 to 250 ° C, the outlet temperature was 100 to 150 ° C, and the disk rotation speed was 8000. Assemble at a condition of ~ 10000 rpm.

Next, press molding is performed. The granulated powder is filled into the form of predetermined size, and a molded object is obtained by surface pressure 700-900 kgf / cm <2>. If the surface pressure is 700 kgf / cm 2 or less, a molded article having a sufficient density cannot be obtained, the surface pressure is not required to be 900 kgf / cm 2 or more, and unnecessary cost and energy are required.

Finally, sintering is performed. The sintering temperature is carried out at 1450 to 1600 ° C, the holding time is 4 to 10 hours, the temperature raising rate is 4 to 6 ° C / minute, and the temperature is performed in a furnace. If the sintering temperature is lower than 1450 ° C, the density of the sintered compact does not become sufficiently large. If the sintering temperature is higher than 1600 ° C, the furnace heater life is lowered. If the holding time is shorter than 4 hours, the reaction between the raw materials does not proceed sufficiently, the density of the sintered compact does not increase sufficiently, and if the sintering time exceeds 10 hours, the reaction is sufficiently occurring, and thus waste of unnecessary energy and time is required. Occurs and is undesirable in production.

If the temperature increase rate is less than 4 ° C./minute, time is unnecessarily required until the temperature reaches a predetermined temperature. If the temperature increase rate is greater than 6 ° C./minute, the temperature distribution in the furnace does not rise uniformly and nonuniformity occurs. The sintered compact thus obtained has a relative density of 98 to 100%, for example about 99.9%, and a bulk resistance of about 0.1 to 3.0 mΩcm, for example about 0.13 mΩcm.

Sputtering  Manufacturing method of target

The manufacturing method of a sputtering target is demonstrated below.

Cylindrical grinding of the outer periphery of the oxide sintered body obtained by the above manufacturing conditions and the surface grinding of the surface side are processed to a size corresponding to a thickness of 4 to 6 mm and a diameter corresponding to the sputtering device, and the indium-based alloy is formed on the copper backing plate. It can be set as a sputtering target by bonding together etc. as a bonding metal.

The sputtering film formation method will be described below.

Using the sputtering target of this invention, the transparent conductive film of this invention is 0.4-0.8 kPa of argon gas pressures, 50-110 mm of targets and a board | substrate space | interval, glass, etc. make a sputter | spatter power non-heating, for example, For example, when target size is 8 inches, it can obtain by sputter film-forming at 200-900W. The sputtering system is preferably a direct current magnetron sputter.

If the substrate spacing is shorter than 50 mm, the kinetic energy of the particles of the target constituent element that reaches the substrate becomes too large, the damage to the substrate is large, the film resistivity increases, and there is a possibility that a part of the film is crystallized. On the other hand, when the distance between a target and a board | substrate is longer than 110 mm, the kinetic energy of the particle | grains of the target structural element which reaches | attains a board | substrate becomes too small, a dense film is not formed and a resistivity becomes high. The appropriate range for argon gas pressure and sputter power is also described above for the same reason. Moreover, when a substrate temperature is also heated, a film | membrane will become easy to crystallize. Therefore, by appropriately selecting these sputter conditions, the film obtained can be made amorphous.

How to evaluate the properties of the membrane

The method for evaluating the properties of the film will be described below.

Determination of the crystallinity of the transparent conductive film obtained as described above includes the presence or absence of a peak as indicated by the crystalline film in the X-ray diffraction measurement (XRD measurement) of the film, and the etching residue as shown by the crystalline film due to the etching of the film by oxalic acid. You can check whether or not. In short, in the X-ray diffraction measurement, when there is no peculiar peak resulting from indium oxide or ITO crystals, and there is no etching residue, the film can be determined to be amorphous.

Film etching method according to the oxalic acid may, for example, with an oxalic acid dihydrate (COOH) ₂ 2H ₂ O pure oxalic acid: pure water = 5: a liquid mixture in a weight ratio of 95, the etchant Trojan a liquid temperature 40 ℃ It can be put into a thermostat so that it may hold | maintain, and the board | substrate with a film | membrane can be stirred and performed.

In addition, the resistivity of a film can be calculated | required by hole measurement. The amorphous film according to the present invention may have a resistivity of 1.8 mΩcm or less, preferably a resistivity of 1.0 mΩcm or less, more preferably of 0.6 mΩcm or less, for example, It has a resistivity of 0.1 to 0.6 mΩcm.

Example

Although an Example demonstrates this invention further in detail below, this invention is not limited to these. That is, all changes and other embodiments within the scope of the technical idea of the present invention are included in the present invention.

(Example 1)

Indium oxide (In ₂ O ₃ ) powders and nickel oxide (NiO) powders as raw materials were weighed in an atomic ratio such that In: Ni = 98: 2, and 3000 revolutions every minute by a super mixer in an air atmosphere for 3 minutes. Was mixed.

Next, water was added to the mixed powder, and the fine powder was pulverized for 2 hours with zirconia beads having a diameter of 1 mm as a slurry having a solid content of 50%, so that the average particle diameter (D50) of the mixed powder was 0.6 µm or less. Thereafter, PVA (polyvinyl alcohol) was mixed at a ratio of 125 cc per kg of slurry, and granulated under conditions of a granulator inlet temperature of 220 ° C, an outlet temperature of 120 ° C, and a disk rotation speed of 9000 rpm.

Furthermore, the granulated powder was filled into the mold of the predetermined | prescribed size used as an 8 inch target diameter, and it pressed at the surface pressure of 780 kgf / cm <2>, and obtained the molded object. And the molded object was heated up to 1540 degreeC at the temperature increase rate of 5 degree-C / min, and after hold | maintaining at 1540 degreeC for 5 hours, sintering was performed by making furnace temperature cold.

Cylindrical grinding of the outer circumference of the oxide sintered body obtained under the above conditions and the surface grinding of the surface side were made, and the thickness was about 5 mm and the diameter was 8 inches, and indium was attached to the copper backing plate as a bonding metal to make a sputtering target.

The sputtering target was mounted on a sputtering apparatus manufactured by Canon Anerva Co., Ltd. SPF-313H, argon gas pressure was 0.5 kPa, target and substrate spacing was 80 mm, and an alkali-free glass was used as a substrate. Was obtained by direct current magnetron sputter deposition at 785 W and deposition time of 22 seconds to obtain a transparent film having a thickness of about 550 GPa. As a result of performing the XRD measurement of the film, no peak showing crystallinity was observed, and the film was amorphous. Moreover, although etching was performed using the liquid which mixed the film in the weight ratio of oxalic acid: pure water = 5: 95, the etching residue was not observed.

The resistivity of this film was 1.2 mΩcm, and the etching rate was 15 Pa / sec. The results are shown in Table 1. Moreover, the transmittance | permeability in wavelength 550nm was 90%.

(Examples 2 to 30)

The sintered compact composition of Example 1 was changed as Table 1, respectively, and what was implemented on the same conditions as Example 1 is Examples 2-30. In all these cases, the film after film formation was amorphous and transparent, and there was no etching residue. The Mn source was manganese oxide (Mn ₂ O ₃ ), the Al source was aluminum oxide (Al ₂ O ₃ ), and the germanium source was germanium oxide (GeO ₂ ), respectively.

In the above results, in these examples, the films after film formation are all amorphous, and the film resistivity decreases once with the increase of the various dopant concentrations or the total dopant concentrations when simultaneous addition of nickel, manganese, aluminum, germanium, and nickel and manganese. Increased after one hour. The dopant concentration which supplies the lowest resistivity was the case of about 6 at%. The resistivity of these films was sufficiently low, low enough to match the resistivity of the ITO film, and was suitable as a transparent conductive film.

On the other hand, the etching rate of the film monotonously increased with the increase in the addition amount of various dopants.

(Examples 31 to 60)

The sintered compact composition of Example 1 was changed as Table 2, respectively, and the other conditions were Examples 31-60 implemented on the same conditions as Example 1. FIG. Although Examples 1-30 were the case where various dopants were added to indium oxide, Examples 31-60 are the Example at the time of adding various dopants to tin dope indium oxide. Tin oxide (SnO ₂ ) was used as the Sn source.

In the above results, in these examples, the crystallinity of the film after film formation is all amorphous, and the film resistivity is accompanied by an increase in various dopant concentrations or total dopant concentrations when simultaneous addition of nickel, manganese, aluminum, germanium, and nickel and manganese, Once decreased, it increased. The dopant concentration supplying the lowest resistivity was about 6 at%.

Moreover, when tin was added, the resistivity of the film | membrane further fell compared with the case where it is not added. The resistivity of these films was sufficiently low and suitable as a transparent conductive film that was low enough to match the resistivity of the ITO film. On the other hand, the etching rate of the film monotonously increased as the amount of the various dopants added increased.

(Comparative Examples 1 to 12)

The sintered compact composition of Example 1 was changed as Table 3, respectively, and the other conditions were the comparative examples 1-12 implemented on the same conditions as Example 1. FIG.

In Comparative Examples 1-5, since the density | concentration of a 1st addition element was too low, a part of film | membrane after sputter film deposition crystallized and the etching residue generate | occur | produced at the time of etching.

In Comparative Examples 6-9, since the density | concentration of a 1st addition element is too high, the resistivity of the film | membrane after sputter film formation is too high and it is not suitable as a transparent conductive film.

In Comparative Example 10, because the concentration of tin was too low, part of the film crystallized, and etching residues were generated during etching.

In Comparative Example 11, since the tin concentration was appropriate, the film resistivity was low and good. However, since the first additive element was not contained, a part of the film after sputtering film crystallized, and an etching residue occurred during etching.

In Comparative Example 12, since the concentration of tin was too high, and because it did not contain the first additive element, the etching rate was very small. Due to the high concentration of tin, the resistivity was also high.

Claims (2)

It contains indium oxide, contains one or more selected from manganese and aluminum as the first addition element, contains tin as the second addition element, and the sum of the contents of the first addition element is indium and the first addition element; It is 2-12 atomic% with respect to the total amount of tin, and content of tin is 2-15 atomic% with respect to the total amount of indium and tin, The amorphous film characterized by the above-mentioned. A substrate is sputtered by heating without using an oxide sintered body having the same composition as the amorphous film according to claim 1 as a sputtering target.